1. Field of the Invention
The present invention relates to the antennas formed by an array of radiating slots made in a wall of a set of microwave signal feeder or collector waveguides positioned side by side. Antennas of this kind are well known in the prior art especially for their ability to be aimed by phase shifts or frequency variation of the microwave signals travelling through their waveguides.
A radiating slot array antenna usually has an entirely metal structure that makes it complicated and therefore costly to manufacture. This entirely metal structure also makes the antenna heavy and therefore difficult to carry and use in mobile equipment mounted on aircraft or land vehicles. It is also difficult for such an antenna to be simply carried by individuals.
2. Description of the Prior Art
There is a known way described in the French patent application FR-A-2.722.337 (THOMSON-CSF) of making slotted waveguides out of a thermoplastic material transparent to microwaves. These waveguides are lined, on the inner wall of their conduit, with a metal skin in which the radiating slots are etched. This technique for making radiating slotted waveguides is used to obtain a lighter material that costs less but is not directly usable for radiating slot array antennas for there arise problems of stiffness of the waveguide assembly supporting the radiating slots. These problems imply the use of a rigid frame that is heavy and bulky.
The idea of making waveguides without slots out of a conduit made of a plastic such as rigid polyvinyl chloride or a stratified polyester, with a metallized inner wall, has also been known much earlier from the French patent FR-A-1.436.490 (GEOFFROY-DELORE).
The present invention is aimed at providing a low-mass and low-cost radiating slot array antenna. A reduction of mass as compared with the standard approach using metal has indeed many advantages. It leads to additional gains in mass on the antenna support and especially on its motor and servomechanism when the antenna is mobile. It also makes it possible to envisage mounting the antenna on a light vehicle or even equipping an individual therewith.